Conveyor system for the uniform exposure of articles or materials to a source of gamma or the like radiation

ABSTRACT

In conjunction with a known or fixed source of radiation, such as gamma radiation, the invention contemplates an automatic conveyor system for plurallike unitary containers laden with articles or materials to be subjected to desired exposure dosage of the radiation. The system accommodates a number of containers at all times, and uniform exposure is achieved for the contents of each container by having all containers follow precisely the same pattern or locus of movement through the system, and with respect to the source. Container movement is accomplished by indexing operations, performed simultaneously on all containers; the desired exposure time is governed by selection of dwell time between indexes, so that a single indexing cycle may serve the system regardless of the selected exposure time.

[ 5] Feb. 8, 1972 United States Patent Armel et al.

CONVEYOR SYSTEM FOR THE [54] Primary Examiner-James W. Lawrence UNIFORM EXPOSURE ()F ARTICLES Assistant Examiner-A. L. Birch I GAMMA OR THE LIKE RADIATION OTHER PUBLICATIONS h l .nmo Ww t a .mmm

, d WW K Y. H N m m mm s o n h m I h 0 M Y B wm. mw m. 0N C Luci m cm ;I I M w a I klw N m m a 0 J38 W m m w t n n g e V S .m A l. I 2 3 7 7 I I [22] Filed: Nov. 3, 1969 [21] Appl. No.: 873,477

ABSTRACT 1968, abandoned.

dosage of the radiation. The system accommodates a number of containers at all times, and uniform exposure is achieved for the contents of each container by having all containers follow precisely the same pattern or locus of movement through the source. Container movethe system, and with respect to 03 mm t ewS Wir USI ,mm mpefl xd .l m m t i mw m e u pfl t g o ww. d..ms g M 6 .m ime u;m w dmfi m n nW .me6 1 y w 3 bmMM dwoma mln m I. .m mdfi C I y mom m M 3 m w wam w de .mm mm lme nUe em hr i .me mS SS XXQ 42 New 802 95" 2 m M m mm C w B nn .moo ums e A M66 r T mufi .m Sfiee e D JJ R m 2 5 6M6 W999 111 III 270 1 l 792 0058 824 l. 64 6 5 333 PATENTEDFEB 8 I972 SHEET 08 [1F 10 CONVEYOR SYSTEM FOR THE UNIFORM EXPOSURE OF ARTICLES OR MATERIALS TO A SOURCE OF GAMMA OR THE LIKE RADIATION This application is a continuation-in-part of copending application Ser. No. 772,111, filed Oct. 31, I968, now abandoned.

This invention relates to a system for the automated production line processing of articles or materials to be exposed to a lo given radiation, such as gamma radiation.

Gamma irradiators in current use are subject to a number of limitations which restrict the efficiency of accomplishing the processing of relatively large quantities of the articles or materials involved. For example, present conveyor systems rely on the rolling or sliding of containers in their movement through the hot or treatment zone, thus inviting wear and eventual breakdown in the critical zone. Such conveyor systems also proceed on the assumption that direct proximity or adjacency of container to the source is the important exposure criterion, thus overlooking fullest use of the available radiation at all times.

It is an object of the invention to provide an improved system of the character indicated, avoidingor substantially reducing the significant limitations of irradiating systems to date.

Another object is to provide such a system in which plural containers for articles or materials to be processed are moved throughout the zone of treatment without involvement of rolling or sliding action; stated in other words, and more specifically, it is an object to provide transport mechanism which relies on the lifting or suspension of each container within the treatment zone, utilizing carrier elements which are externally actuated, so that servicing of the transport mechanism may be performed externally of the treatment zone.

It is also an object to provide in a system of the character indicated such a relationship between configuration of the source, of the basic containers, and of the nested accommodation of plural containers in the treatment zone, that the contents of each container will receive not only substantial uniformity of radiation exposure throughout the loaded volume of the container, but the loaded contents of each successive container will also be given the same uniformity of exposure.

A further object is to provide for readily adjustable selection of exposure time for the production-line handling of successive runs of different materials through an irradiating processor of the character indicated; specifically, it is desired to achieve this object totally without resort to variable feed rate or the like techniques.

Another object is to provide, in an irradiator of the character indicated, a transport or conveyor system of basic modular configuration which lends itself to provision in multiple in a given irradiation chamber, should expanded capacity be indicated.

It is a specific object to achieve the foregoing objects with a maximum efiiciency of utilizing the radiation from a given radiation source capacity.

It is a general object to achieve the above objects with a system of elemental simplicity and reliability, lending itself to highly efficient and, therefore, economical use of the available radiation, and at the same time having high productivity of uniformly irradiated articles or materials; it is an object to achieve such results with a system which requires a minimum of supervision and which can automatically handle large unattended runs, as, for example, round-the-clock operation and for holiday periods.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, a preferred form and modification of the invention:

FIG. 1 is a simplified isometric view of a gamma irradiation plant of the invention, certain parts being broken away and others omitted to permit identification of internal parts and relationships;

FIG. 2 is a simplified plan view of the plant of FIG. 1, certain parts being broken away and others omitted;

FIG. 3 is a simplified view in elevation, as seen from the nearby end of FIG. 2;

FIG. 4 is a simplified schematic layout of container positions relative to the source, as viewed from 44 in FIG. 5;

FIGS. 5 to 8 are similar simplified views in elevation, showing container transport mechanism of the invention, for each of a succession of displacements involved in an indexing cycle for the progressive transport of a plurality of containers in the irradiation cell of FIGS. 1 and 2;

FIG. 9 is an enlarged vertical sectional view through the transport mechanism, taken from the frontal aspect of FIGS. 4 to .7 but in the central vertical plane of general symmetry;

FIG. 10 is a sectional view taken in generally the plane 10- 10 of FIG. 9;

FIG. 10A is a plan view of upper parts of elevator structure at the right-hand portion of FIG. 9;

FIG. 11 is a fragmentary view in elevation, showing part of elevator support structure for the transport mechanism of FIGS. 9 and 10, the aspect looking left, from the upper right of FIG. 9;

FIGS. 12 to 15 are simplified views to illustrate various actuators and limit switches involved in automated operation of the transport mechanism, FIG. 12 being a plan view of the irradiation cell with parts broken away to show container inlet detail, FIG. 13 being taken as a section at 13-13 in FIG. 12, FIG. 14 being a front elevation, and FIG. 15 a left-end elevation;

FIG. 16 is an electrical ladder diagram to show interrelated control functions for operation of the transport mechanism;

FIG. 17 is a timer program layout for determining sequenced operations in a given cycle of operation;

FIG. 18 is a simplified plan view of a cell containing modified transport mechanism, the walls of the cell being broken and in section at essentially the plane I8-l8 of FIG. 19, for better showing of cell contents;

FIG. I) is a simplified diagram to graphically depict the path of transport of containers processed in the cell of FIG. 17;

FIG. 20 is a simplified isometric view of elements of a modified gamma irradiation plant of the invention, effectively doubling the radiation capacity for a given irradiation source, and shown utilizing an in-cell conveyor system having essentially the appearance of FIG. 19, as to container path elevation;

FIG. 21 is a view similar to FIG. 4 but applicable to the modification of FIG. 20;

FIGS. 22 to 27 are simplified like diagrams schematically depicting a succession of events in an indexing cycle of the modification of FIG. 20, the aspect of view being generally at a section taken in a vertical plane through inlet and outlet ports of the cell;

FIGS. 22A and 26A are enlarged simplified fragmentary right-end views of parts of FIGS. 22 and 26, respectively; and

FIG. 28 is a timer program layout for additional functions of FIGS. 20 to 26, applied to the program and cycle of FIG. 17.

Briefly stated, the invention contemplates supporting and transport (or conveyor) mechanism for the uniform handling ,of materials or articles to be subjected to strong radiation, as from a cobalt-60 source, contained within a suitably shielded irradiation cell. The invention utilizes a standardized container, transparent to the radiation and provided in multiple, for the production line handling of the materials to be processed. The size and proportions of the basic container are related to the effective dimensions of the source and to the pattern or locus of container movement in and through the cell, as part of the production line handling. The system accommodates a number of containers within the cell, at any given time, so that in some measure the contents of all containers within the cell are being exposed to various radiation flux densities and from various aspects of incidence. The locus of transport is such that all containers progressing through the system will receive precisely the same total exposure, from all possible aspects, as long as care has been taken to uniformly load all containers in the first place. Container movement is accomplished by indexing operations, performed simultaneously on all containers, and the desired exposure time is governed by selection of dwell time between indexes. The same single indexing cycle may thus serve the system regardless of the selected exposure time.

Referring to FIGS. 1, 2 and 3, the invention is shown in application to a gamma irradiation plant utilizing a relatively thin elongated radiation source 10, as of cobalt-60. Suitable shielding walls 11 surround the source and define an irradiation cell having an inner volume 12 for reception of transport mechanism for materials or articles to be exposed to source 10. Source 10 will be understood to be a plaque or array of a large plurality of like source elements meeting the foregoing description, in terms of its effective area; the effective radiation surfaces of source 10 are shown in a horizontal plane, providing radiated flux distributions alike, primarily in regions above and below such plane. Supporting means for source 10 is omitted from the diagrams, although a cask element 13, which in turn is received in one of the walls 11, may provide some of the support for source 10.

The basic element of the transport mechanism is a box or container element, as of aluminum or other material transparent to the radiation. Such boxes are provided in duplicate, as necessary, to enable a steady continuous stream or succession of boxes to be conveyed through the system. For the form shown in FIGS. I to 3, the transport system has a capacity of 24 such loaded containers at any one time. In FIG. 1 (and in FIGS. 4 to 8) the boxes depicted within the cell, for a given cycle of operation, are given specific identifying box numbers, namely C-l to and including C-25. The box labeled C-25 will be understood to be the one just entering the transport mechanism 14 (identified generally in FIG. 2) within cell 12, and the box labeled C-l will be understood to be the one which has completed its exposure and is about to be discharged.

The supply of loaded containers to cell 12 and their withdrawal after processing are accommodated by external handling mechanism which may be located in a single handling space, shed, or room, to one side of one wall of the cell. In FIG. 1, building walls or partitions 15-15, contiguous to one cell wall, suggest such a layout, servicing an inlet port or passage 16 and an outlet port or passage 17 in the cell wall 18. In FIG. 2, it is suggested that one of the short walls of the cell 12 may be removable, as by manual building block assembly of plural layers of shielding elements 19, for installation, servicing and maintenance purposes. The outer wall 11 may be suitably capacitated, as suggested at 20, for the removable insertion of different sources 10, each with its cask 13, as may be necessary from time to time.

Containers are shown loaded and ready for treatment in a battery or loading magazine, comprising plural gravityoperated roller conveyors 21-22, serving an arterial conveyor 23 to an elevator 24, for raising successive loaded containers to an elevated horizontal feeder or magazine element 25. The last container 26 on feeder 25 is always positioned against a fixed stop 27 in poised alignment with the inlet passage 16 and with the piston rod or actuator of hydraulic cylinder 28; the latter can be suitably termed the incoming transfer cylinder, for applying displacement to container 26, as part of the inletloading operation.

FIG. 1 has been indicated to be schematic in nature, and this is particularly true as to the incoming-transfer mechanism, driven by cylinder 28. The main point is that for each indexing cycle there shall be a cycle of reciprocation by cylinder 28, and that the latter shall be effective to transfer to the loadin" position (in the cell interior 12, FIG. 1, this is the container position marked C-25) the next available loaded and unexposed container. If the stroke of cylinder 28 were long enough, then its stroke could transfer the available container 26 all the way through inlet 16, to the position identified C-25 in FIG. 1; however, I prefer to accomplish such loading transfer with a cylinder 28 that is merely long enough to place the container 26 on a driven-roller transfer system, operative within the thickness of the cell wall, at passage 16, and at the load-in position of the transport mechanism 14; these roller transfer mechanisms are not shown in FIGS. 1 to 3 but will be described in connection with FIGS. 9 to 11. At present, it suffices to state that a first indexing actuation of cylinder 28 (in conjunction with the driven-roller system within passage 16) may displace container 26 to an intermediate location 26'. within inlet 16 and fully contained between inner and outer surfaces of the cell wall 11. To accommodate this displacement, an outer shielding door 36 will have been displaced to open the inlet 16, while an inner shielding door 35 is kept closed, as shown in FIG. 1. Once the container is at the in-wall position 26', door 36 is closed, door 35 is opened, and then the driven-roller systems are operative to transfer the container from the position 26 to the load-in position at C-25 in FIG. 1. The load-in function will be seen as coordinated with a radiation lock or trap, and the heavy arrow 28 will be understood as a schematic designation of means coordinated with the transfer stroke of actuator 28 to achieve the indicated door-operating and loading-transfer functions, in such sequence that the interior of the cell is never externally exposed.

On completion of exposure within cell 12, the applicable container C-l has arrived at its position (within mechanism 14) in alignment with the exit passage 17, and exit transport mechanism (not shown in FIGS. 1, 2, or 3) and a poweredroller conveyor 29 in passage 17 are operative to discharge the processed container to an arterial gravity conveyor 30, for distributed storage in one or another of plural gravity conveyor racks 31-32. The treated contents may, if packaged, be removed for immediate shipment, or if the material has been processed in bulk, it may be removed for packaging or other loading, as best suited to the desired mode of delivery to the customer.

The basic handling technique involves selected uniform dwell periods between standardized index cycles, all motions and synchronizing functions being achieved during the indexing interval, as will be later explained in connection with an illustrative program (FIG. 17). It suffices at this juncture to identify an illustrative unit container release means 33, for releasing successive untreated container loads, one per index cycle, from one of the conveyors 21-22 to the arterial conveyor 23, it being understood that suitable interlock devices (not shown) are employed as necessary to assure a steady supply of containers to elevator 24. The elevator will be understood to include suitable actuating means, also operative once per indexing cycle, for raising one further (i.e., the next available) container to the level of conveyor 25. An elevator transfer cylinder 34, operative on the most recently elevated new container, transfers the same from the elevator platform to the conveyor 25 and at the same time imparts indexing displacement of all containers on conveyor 25, to the point of arrest of container 26 at stop 27.

In the period between indexes, i.e., in the periods of primary exposure to source 10, suitable radiation shields or doors are placed over the inner and outer ends of inlet and exit passages 16-17. The inner and outer inlet shields 35-36, and the outer exit shield 37, are identified in FIGS. 1, 2, and 3 (the inner exit shield 38 is identified in FIG. 15); each of these shields is shown suspended by its own overhead rail system for horizontal reciprocation, once per indexing cycle, to open and close the inlet passages 16-17 for container transfer, the sequencing being such as to assure the radiation lock function already referred to. The several hydraulic actuators for these shields are identified as follows:

39, for the inner inlet shield 35 (FIG. 14),

40, for the outer inlet shield 36 (FIGS. 3, I4),

41, for the outer exit shield 37 (FIGS. 3, 14),

42, for the inner exit shield 38 (FIG. 14).

The incoming-transfer cylinder 28 has already been identified; it operates once per indexing cycle, as also does the exit transfer mechanism (FIGS. 9-10), to be later described. Finally, to complete the identification of elements synchronized with indexing, I illustrate at 44 another transfer cylinder, which may be one of a plurality serving the respective storage conveyors 31-32 for processed loaded containers.

THE CONVEYOR MECHANISM 14 IN GENERAL, AND ITS RELATION TO SOURCE 10 In FIG. 1, the locus or path of movement for containers progressing through their radiation exposure within cell 12 is indicated by a series of arrows. At any one given period of dwell time, i.e., between index cycles, the accommodation of containers can be said to comprise two like clusters or matrices of containers, one above the plane of source 10, the other below the same. For the 24-unit capacity shown, there are four rows of three containers in each cluster. The containers are in close side-by-side adjacency, with interlaced opposite lateral offsets of the odd container in each successive row or tier. The arrangement is such that double aligned vertical columns or stacks of containers are symmetrically disposed with respect to the source 10. Upon indexing, each container is bodily displaced substantially to the extent of one unit container dimension, in the direction indicated by the sequence of arrows in FIG. 1. The unexposed container C-25 has thus just entered the open spot in the top tier of the upper cluster, and the fully exposed container C-l is about to be withdrawn through the exit passage'17; this happens also to be the instant of time depicted in FIG. 6.

FIG. 6 is the second of a sequence of four simplified diagrams (FIGS. 5 to 8) which will be helpful in identifying important parts of the cell conveyor system and in demonstrating actuating sequences in the index cycle, and FIG. 4 is helpful in explaining orientation with respect to the effective area of the source 10.

In FIG. 4 which shows only the containers in the left vertical stack of FIG. 5, namely, containers C-3, C-5, C-9, C-ll, C-15, Cl7, C21, and C23, all containers have an effective length dimension L,, which is less than the effective length dimension L of the source 10; in FIG. 5, the effective container width W is shown to be substantially the same as the effective width dimension W of the source 10. Each container end is provided with a projecting lug, as at 45, for manipulating purposes. By relying on such lugs for manipulation, the vertical space between tiers can be kept to a minimum, so that the capacity of the container clusters is determined largely by the effective container height H The extent by which the effective source length L overlaps and projects beyond each container end is in the range of 5 to percent of the effective container length L Such projection will be seen to provide added measure of radiation flux incident upon the adjacent ends of container loads, thus making up for end effect falloff in the flux density distribution which would apply for more nearly equal effective lengths Is -L we find that the indicated geometry achieves substantially uniform flux density for the entire volume of uniformly laden containers which have followed the course of my cell conveyor system.

Basically, the mass indexing of all 24 containers is accomplished by a complex of horizontally guided push bars, which are reciprocated in phase interlace with the reciprocation of a series of vertically guided elevators. At this juncture, it suffices to identify fixed upstanding frame structure including left frame means 50, center frame means 51 and right frame means 52, for the respective vertically guided support of a left elevator 53, a center elevator 54 and a right elevator 55. Each end elevator 53-55 has brackets appropriate to the location and spacing of adjacent laterally offset container positions in the rows of tiers served thereby; the center elevator 54 has means (to be later described) for simultaneously engaging and lifting and lowering all containers in the double vertically aligned container stacks of both the upper and lower container clusters.

The push bar system comprises left-hand and right-hand arrays of horizontal rod systems. For the left-hand push bar system 56, four rigidly connected horizontal bars 57-58-59- 60 serve odd-numbered tiers for containers in both clusters, i.e., above and below the source 10. These rods or bars are provided in duplicate and are guided in the upstanding frame structure, being positioned beneath the container lug alignments for each of the associated tiers; typical of such relationship is a simplified illustrative detail, shown in FIG. 4 at the right-hand end of container C-23, where the push bar 60 is seen as an elongated angle member having its horizontal flange poised to receive and support the adjacent container lug 45 when the center elevator is actuated to its down position, at which time the outer lug-engaging flange of the channel-shaped lifting member 61 (of elevator 54) will have cleared the container lug 45.

The bars or rods 57-58-59-60 of push bar system 56 are of effective length to engage under lugs 45 of containers in the far right alignment (i.e., the verticalalignment of containers C-25 and C-1 in FIG. 6) when the push bar system 56 is actuated to its right limit; at its left limit of reciprocation, the Push Bar Out position of FIG. 6, the ends of bars 57-58-59- 60 all clear this far right lug alignment. At all times, however, these bars are poised to support the container lugs for all other vertical container alignments in the upper and lower clusters.

The right-hand push bar system 62 meets generally the description given for system 56, except that its horizontal bars 63-64-6566 serve tiers interlaced with those served by bars 57-58-59-60, and the reciprocation of system 62 is in phase opposition to that of system 56. In FIG. 6, both push bar systems 56-62 are shown in their out positions, the bars 57-58-59-60 of system 56 being out of possible engagement with container lugs in the far right vertical alignment, and the bars 63-64-6546 of system 62 being out of possible engagement with container lugs in the far left vertical alignment (of containers C-4, C-10, C-16, C22); simultaneous actuation of both push bar systems brings all bars into support relation for all containers in both clusters.

The left elevator 53 includes vertically spaced shelves or brackets 676869-70 serving the adjacent ends (far left vertical alignment) of containers in the even-numbered tiers in both clusters. In the Left Elevator Up position shown in FIG. 6, these brackets are carrying the containers C-4, C-10, C-16, C-22. The left elevator 53 is used to transfer these containers from the even-numbered tiers (shown in FIG. 6) to the odd-numbered tiers (as shown in FIG. 7).

The right-hand elevator 55 is of generally the nature described for the left elevator 53; it serves the far right vertical container alignment and is used to transfer containers C-7, C-l3, C-l9, C-25, from odd-numbered tiers to the lower adjacent even-numbered tiers (the problem of handling the last and fully exposed container C-l will be covered in later description). Since this transfer movement involves a larger displacement between the fourth and fifth tiers (spanning source 10) than applies for the space between tiers of a given cluster, the righthand elevator system should be able to handle both kinds of displacement for a given single stroke of the right-hand elevator system 55. In the form shown, this problem is resolved by provision of a lost-motion relation between an auxiliary elevator structure 71 (wit its container support shelves or brackets 72-73, shown serving containers C-7 and C-19) and the primary right-hand elevator system 55 (with its container support shelves or brackets 74-75, shown serving containers C-13 and C-25), as shown in FIG. 6. The primary system 55 has a Right Elevator Stroke adequate to transport container C- 13 from the fifth to the fourth tier (FIG. 6 position to FIG. 7 position), and the lost-motion relation between auxiliary 71 and its primary structure 55 is such as to accomplish a lesser Partial Stroke" appropriate to the intertier spacing within a given cluster.

Having thus identified important parts of the transport mechanism, an index cycle will be described in connection with the interlaced orthogonally related reciprocating cycles involved. The mechanism will have been in the FIG. 8 condition for the dwell period preceding index, i.e., with all three elevators 53-54-55 in their respective down" positions, so that all containers are supported by the push bar systems 56-62, and with the push bars all "in" (i.e., in registration with all container lugs 45). FIG. depicts the first indexing step, wherein the elevator systems 53-54-55 are actuated to their respective up" positions, in directions indicated by large arrows. This brings the upper bracket 75 of the primary system of the right-hand elevator 55 up to its top position, in readiness to receive the new unexposed load-in container C-25 (FIG. 6). As will later be made more clear, the fully exposed container C-I, in the bottom right position shown, is held up by mechanism related to the auxiliary elevator structure 71 (to be described in connection with FIGS. 9 and 10).

The next step in the indexing cycle is illustrated in FIG. 6, wherein the push bar systems 56-62 are actuated to their respective Out positions, in directions denoted by large arrows. It will be recalled that in this relationship the effective ends of bars 57-58-59-60 all clear the extreme right vertical alignment of container lugs at C-l, C-7, C-l3, C-l9, and that the ends of bars 63-64-65-66 similarly clear the extreme left vertical alignment of container lugs at C-4, C-10, C-16, C-22. Of course, the push bar system displacement of FIG. 6 resulted in no change of position by any containers, except that the newly introduced unexposed container C-25 will have been brought into position on the upper right bracket 75.

The third step in the indexing sequence is illustrated in FIG. 7, wherein heavy directional arrows indicate that all three elevator systems 53-54-55 have been actuated to their down" positions, to different extents indicated by appropriate legends in FIG. 6. These downward displacements have brought all container lugs 45 into intercepted support by the nearest lower push bar, freeing all containers from elevator support. Thus, the newly introduced unexposed container C-25 is brought down to supported relation on upper bars 66 of the push bar system 62; the partially exposed container C-22 is brought from the topmost tier down to supported relation on the upper bars 60 of the push bar system 56, at the elevation of the next lower tier; and at the same time, containers C-l9, C-16, C-l3, C-I0, C-7, and C-4 are brought down into supported relation with bars 65-59-64-58-63-57, respectively. Also, parenthetic note is taken that in the course of the right elevator downstroke of FIG. 7, the fully exposed container C-l is deposited on exit transfer mechanism, to be later described but symbolized in FIG. 7 by contact with the powered exit roller conveyor 29, in alignment with further exit roller mechanism 29 within the cell wall exit passage 17. Thus, when the step of FIG. 7 is accomplished, the space previously occupied by the fully exposed container C-I will have been vacated.

The last step in the indexing cycle is depicted in FIG. 8; it involves the simultaneous inward displacement of both push bar systems 56-62, as suggested by the heavy directional arrows at both sides of the diagram. In these displacements, all three containers which happen to be carried by each push bar (such as containers C-23, C-24, C-25 on push bar 66, and containers C-20, C-21, C-22 on push bar 60) are bodily displaced, effectively to the extent of one unit container width, thus shifting the stack makeup for the dual vertical alignments of containers served by the center elevator system 54. It will be appreciated that this shift positions container C- to the right and above the source 10, so that during the next ensuing dwell between indexes container C-15 will receive the substantial balance of its exposure to source 10, from its locations of adjacency above the source. At the same time, container C-12 which has already received all of its exposure from above source 10, plus a substantial left-half exposure from below source 10, is shifted to receive the substantial balance of its right-half exposure to source 10. All other containers have been shifted to add to their total variety of radiation flux density and incidence direction, to the point where container C-2, being almost completely exposed, is moved to the terminal (bottom right) matrix storage position. The cycle of index has now been completed, and a dwell for exposure is allowed to take place.

TRANSPORT MECHANISM 14, IN GREATER DETAIL FIGS. 9, l0, and II show greater detail for the transport mechanism 14. These figures depict the preferred form as to such detail, the minor variations which may be observed between structure already described and that of FIGS. 9, I0 and II are due to an understandable need for simplicity in connection with the generalized discussion which was needed for an initial appreciation of the overall cooperation between important elements of the total mechanism.

The principal difference involved in the detailed mechanism of FIGS. 9, 10, 11 resides in the two push bar systems, which are still interlaced in their placement and action but which are actuated from ends opposite to those discussed in connection with FIGS. 5 to 8. Thus, the push bar system 56 comprising bars 57-58-59-60 is rigidly tied together by framing 76, for reception of double-acting hydraulic actuation via a rod 77 associated with an actuating cylinder 78 (FIGS. 12, 13), mounted at the outside of the cell wall 11. Similar hydraulic actuating means 79 (FIGS. 12, 13), including an actuating rod 80 and framing 81, connects the push bars 63-64-65-66 of system 62, for unitary displacement.

All push bar structures are guided on spaced framemounted rollers, as at 82-83 for the respective left and right ends of the push bar 57, and a detailed description of push bar 57 will suffice. Push bar 57 happens to be the one which appears in full plan view, for the section depicted in FIG. 10.

Referring primarily to FIG. 10, the illustrative push bar 57 is seen to comprise two like elongated angle members or rails 84-85, rigidly tied together at one end by a crossmember or channel 86. Members 84-85 have the extent and the effectiveness discussed for bar 57 in connection with FIGS. 5 to 8, and in FIGS. 9-10 these members 84-85 of bar 57 are shown in the out" position, discussed for bar 57 in FIGS. 5-6. The bottom inwardly facing horizontal flanges of rails 84-85 are relied upon to support containers by their lugs 45; therefore, for the out position shown in FIGS. 9-10, these horizontal flanges terminate (as at 85, for rail 85) at a location to clear the vertical alignment of container lugs in the extreme right alignment served by the right elevator system 55. To maintain rigidity for the push bar 57, it is preferably a completed rectangular frame which permits the desired clearance at elevator system 55. In FIG. 10, this relation is achieved by use of auxiliary angle member or rail lengths 87-88, secured as by welded overlap with the adjacent end (85') of rails 84-85 and tied together by a crossmember or channel 89, beyond the right-hand upstanding fixed frame members 52; lengths 87-88 overlap the outer vertical flanges of rails 84-85, and their horizontal flanges face outwardly, away from each other, to define the desired clearance with container lugs 45. The rigid connection of push bar 57 to the other similarly constructed bars 58-59-60 serving the push bar system 56 is completed by spaced vertical angle members or rails -91 secured to the right-hand crossmembers, such as 89; the rails 90-91 are in turn connected at substantially the midvertical location by a transverse channel 92 suitably fitted at its center to receive the double-acting displacement actuations of rod 77.

The fixed framing relied upon for the guided alignment and support of the push bar systems 56-62 is also shown in detail in FIGS. 9 to 11. Basically, such framing relies on the left, central, and right upstanding members 50-51-52 already identified. Of these, the end upright members 50 are provided in duplicate, spaced from each other, as are the similar end uprights 52; the central uprights are shown in quadruplicate, at the four corners of a two-dimensional spacing (see FIG. 10). The end-upright framing additionally comprises interconnecting transverse channels, as at 93 for the uprights 50, and at 94 for the uprights 52. Spaced vertical girders 95 are secured to outer projecting ends' of channels .93, for rigid center location of the push bar guide rolls 82, which serve the rails 84-85 of push bar 57 and its family of related push bars 58-59-60. In similar fashion spaced vertical girders 96 are secured to outer projecting ends of channels 94, for mounting the push bar guide rolls 83 which serve the rails 87-88 of push bars 57-58-59-60. The only difference between guide rolls 82-83 is the extent of their offsets from their respective supporting upright girders, as indicated by the local adjacent inward or outward direction of the push bar rail flange involved. In FIG. 11, it is seen that each of the uprights, such as one upright 96, mounts guide rolls 82-83 of both degrees of offset, due to the interlaced nature of the effective spans or lengths of push bars in the respective systems. Thus, in FIG. 11, the lowermost roll 83 (short offset) guides the rail extension 88 of push bar 57; the next higher guide roll 82 (greater offset) guides the primary effective rail length of the push bar 63. The two degrees of roll offset continue to alternate with each higher tier to serve rails of the remaining push bar frames 58-64-59-65-60-66, generally designated in their order of interlaced ascendency. Rugged structural integrity as between all upstanding elements of the frame structure is completed by plural vertically spaced horizontal channel members 97-98; on one side, channels 97 interconnect the central uprights 51 and the projecting ends of crossmembers 93-94 at uprights 95-96, and channels 98 interconnect corresponding parts on the other side of the frame.

It is seen that spaced guide roll suspension for all push bars assures virtually frictionless lateral displacement of the containers within the transport matrix. This naturally means that relatively small hydraulic actuating forces can achieve rapid and efficient motion, even for loaded push bars (i.e., proceeding from the FIG. 7 to the FIG. 8 relationship). To assure that such translation shall be positive and free of skid on rails of the push bar, I show at 99 on rails 84-85 (FIG. the provision of suitable keying means such as local welded pads, spaced to define locating slots for positive location of the container lugs 45 during horizontal indexing displacements. A Sa-inch height for such pads 99 suffices for the desired locating result, in the circumstance of a center elevator lift stroke of about 1 inch; this relationship assures nonfouling action as described for the interlaced horizontal and vertical strokes which characterize each index cycle.

The remaining mechanical structure of the transport mechanism 14 involves the several elevator systems 53-54-5 5. The left elevator 53 comprises spaced elongated vertical members 100-101, cross-connected at 102-103 and by a beam 104 having a suitable central connection to the rod 105 of a hydraulic actuator 106 mounted on the roof or exterior of the cell 11 (see FIGS. 12 to Guide blocks 107-108, which may each include antifriction elements (not shown), are provided at upper and lower spaced locations on vertical members 100-101 to track the vertical frame alignment of rail elements, as at 109, forming part of the upright frame members 50. The individual shelves or container supports 67-68-69-70 all suitably derive fixed bracketed support from the elevator framework 100-101-102-103-104; they move in unison in accordance with actuation at 105.

The center elevator 54 comprises an open rectangular prismatic frame for the unitary support and short stroke vertical reciprocation of the lifting channels or lugs 61. The channels 61 are shown cross-connecting spaced elevator uprights 110-111, at the respective front and back extremes of the elevator 54. Welded crossed I-beams 112 provide diagonal rigidity at the lower end of elevator 54, and similar structure 113 serves at the upper end. The intersection of upper beams 1 13 is suitably adapted for actuation by a rod 114 forming part of a center elevator hydraulic actuator 115, shown in FIGS. 12 to 14 to be mounted on the roof or exterior of the cell 11. Vertically spaced shoes 116 (on the elevator uprights 110-111) ride vertical comer guides 117 (on the fixed frame uprights 51), for assured vertical orientation and lateral stability. For additional rigidity of the center elevator guiding framework, upper projecting ends of the uprights 51 are interconnected by spaced pairs of channels 118-119; similar pairs of channels 120-121 interconnect lower ends of the same uprights 51.

The remaining or right-hand elevator system has been described as comprising a primary elevator 55 (including container supports 74-75) and an auxiliary elevator 71 (including container supports 72-73). The primary elevator receives its stroke from a vertical actuator rod 122, forming part of an externally accessible hydraulic actuator 123 (FIGS. 12, 13, 14) and having the stroke indicated by legend in FIG. 5. The auxiliary elevator 71 has a lost-motion relation to elevator 55; its lesser strokederives from displacement of rod 122 but is substantially only to the extent of tier-to-tier spacing.

Both right-hand elevators 55-71 derive vertically guided support from the upright guides 52, forming part of the basic fixed framing and otherwise connected thereto by means of the upper and lower transverse members 94. Suitably spaced guides on each of these elevators ride the two vertical guides 52, as shown at 124 for the case of the auxiliary elevator 71; preferably, such guides 124 are provided at each container support region for each of the elevators 55-71, those shown in FIG. 10 being the ones in the vicinity of the container support or shelf 72.

The framed structure of the primary elevator 55 comprises laterally spaced upright sideplates 124, connected at their upper end by a transverse channel 125, to which the actuating rod 122 is centrally connected, at the region of the upper container support 75. The lower end of side plates 124 is con nected by the vertical wall 7 4' of the lower container support 74 and by a crossbar 126, offset to the rear from the wall 74' so as to define a suitable clearance for free passage of vertical members 127 of the auxiliary elevator structure 71. Gussets or bracket members 128 at the respective ends of the support 74 provide firm container support as well as an upper abutment edge 129 for interference with the lower edge 130 of similar reinforcing end bracket members 131 of the upper container support 73 which forms part of the auxiliary elevator 71. Structural integrity of the primary elevator 55 may be enhanced by diagonal bracing in the vertical plane of the crossbar 126 and in the region defined by the sideplates 124 and the crossmembers -126; for clarity in the drawings, such diagonal bracing has been omitted.

The vertical side members 127 of the auxiliary elevator 71 have already been identified. These side members form, with suitable crossmembers and diagonal bracing (not shown), a rigid frame which is vertically movable within the clearance afforded by the offset of crossbar 126 behind wall 74', and within the span between the primary elevator sideplates 124. The lower container support 72 and its backwall 72' may form part of this cross connection and may be permanently secured to the side members 127, and for ease of assembly the upper container support 73 and its backwall 73' may be removably secured to the described framing of elevator 71; however, in the form shown and for clarity in the drawings, the upper container support 73 is permanently secured to and forms part of the structural integrity of the auxiliary elevator structure.

In addition to the described parts, the auxiliary elevator 71 further includes a still lower level of container support, coacting with the exit roller means 29, to achieve automatic removal of a fully processed container. In FIGS. 9 and 10, this lowest support level is established by an array of like spaced brackets131, forming a rigid forked structure depending from the auxiliary elevator; as shown, a vertical plate 133 is reinforced, at each alignment with a bracket 131, by a narrow vertical channel 134 extending substantially to the support plane of edges 131' of brackets 131. In the spaces between adjacent brackets 131 and their reinforcements 134, the place 133 is vertically slotted, for clearance with adjacent rollers of the frame-based exit roller system 29. In the process of displacement from the upper support plane 132 of brackets 131 (where a processed container C-1 is received from the con- 1 1 tainer transport matrix) to the lower position shown in full lines in FIG. 3, the support plane 131 will have passed below the support plane of the exit roller system 29, thus enabling the exit roller system 29 to remove the exposed container C-I.

The exit roller system 29 is seen in FIG. to comprise plural spaced rolls 135, journaled at both ends in the frame, as in bearings carried on transverse connecting members 136-137, the roll spacings being in accordance with the spacings between brackets 131, at locations interlaced between the bracket locations. Beveled guides 138 on each roll 135 locate opposite sides of the container to assure desired alignment of the container as it is carried by the exit conveyor system 29. Drive to all the rolls 135 is accomplished by sprocket interconnections 139 between adjacent rolls, and by a driven shaft connection 140 to one of the central roll shafts; motor means (not shown)'may be provided external to the shaft 140 for supplying continuous drive for the system 29.

In a manner similar to that described for the exit roller system, the incoming loading platform 75 of the primary righthand elevator 55 may be characterized by a series of spaced driven conveyor rolls 131, best shown in the plan view of FIG. 10A. The platform 75 may thus comprise a rigid open rectangular frame, defined by side members 142-143 and by end members 144-145. The plural spaced rolls 141 are joumaled at both ends in the frame members 142-143, and they are driven in unison by sprocket connections 146 and by an external drive shaft connection or fitting 147 to one of the central roll shafts; it will be understood that the drive shaft connection to the fitting 147 should be flexible, to accommodate itself to elevator cycling, as by employment of flexible shafting, universal jointing, etc., (not shown).

The direction of drive at 147 is such as to advance the incoming container C-25 in the direction shown by the heavy arrow in FIG. 10A. Such drive is of course initially imparted by the drive roller system already referred to in connection with transferring the container out of the in-wall position shown at 26' in FIG. 1. During this transfer, the front edge of the container will first intercept platform 75 at a latch I48 forming part of the end 145 of the platform frame; it will be understood that the upper edge of latch 148 projects above the support plane of rolls 141 and that it is sloped so as to be cammed downwardly as the container enters platform 75. In the form shown, latch 148 is pivoted on a horizontal axis 149 and is resiliently urged (by means not shown) to the upper or latching position. When the newly loaded container is fully transported (onto platform 75), it strikes abutment stops 150, determining correct placement for indexed handling within mechanism 14; at this point, the rear edge of the new container clears the latch 148, allowing for automatic locating reference of the container in the C-25 position. It will be understood that limit switch or like probe means (LS-22) may sense the accomplishment of the correct container position and may suitably deenergize or declutch the roll drive system; alternatively, the drive to fitting 147 be an electric motor of the so-called stalled-torque variety, so that as long as the container is held on platform 75, it will be continuously urged against the positioning stops 150. Of course, as the described indexing cycle progresses, from the container load-in situation depicted in FIG. 6, to the push bar supported situation depicted in FIG. 7, container C-25 is relieved from support by the rolls of platform 75, and (in the event of a stalled-torque motor drive) a no-load condition is restored for the drive to rolls 141.

CONTROL SYSTEM It has been generally indicated, as a feature of the invention, that exposure of container contents is regulated by the selection of dwell time between indexes. In other words, no matter what the selected dwell time (manual selection of setting of Timer Relay TR at L-27 in FIG. 16), the indexing operation will proceed in the same automated cycling sequence. The various actuators involved in indexing may be electric, electromechanical, or hydraulic, but they all accomplish mechanical displacements which may be monitored by limit switches; these switches form part of an electric control system which employs a series of electric relays and solenoids for hydraulic valves. For ease of identification, the limit switches are given the designation LS followed by a number, the relays bear the numbered designation R, and the hydraulic valve solenoids bear the numbered designation SOL; in the ladder diagram of FIG. 16, the numbered symbol L identifies successive circuit lines, and the various contacts of the several relays are identified by the applicable relay designation, followed by hyphenated enumeration. A diagonal slash line through particular contact lines designates the normally closed nature of the contacts; the absence of such a slash line connotes the normally open nature of the contacts.

The control parts can perhaps best be understood in terms of their relation to certain of the limit switches, which will first be more or less sequentially identified:

a. LS-l0 and LS-ll respectively monitor the full open condition of the outer shield doors 37-36.

b. LS12 and LS13 respectively monitor the stroke condition of the load-in actuator 28, LS-12 closing when the full load-in stroke is accomplished, and LS13 opening when the actuator 28 has fully retracted.

c. LS-l4 and LS15 respectively monitor the closed condition of the outer entrance and exit shield doors 36-37.

(1. LS16, LS-17, and LS-18 respectively monitor the UP" positions of the right-hand elevator system 55, the central elevator 54, and the left-hand elevator 53.

e. LS20 and LS-2l respectively monitor the OPEN" positions of the inner shield doors 35-38.

f. LS-22 is a normally open switch shown in FIG. 10A (and at L-22 in FIG. 16) which is mounted on the frame of the load-in platform 75 and which monitors container abutment at stops 150.

g. LS-23, LS-24, and LS-ZS respectively monitor the DOWN positions of the three elevator systems (see FIG. 13).

h. LS-32 and LS-33 monitor the outward positioning of the push bar actuators 78-79 (see FIG. 13).

The chart of FIG. 17 depicts the automated sequencing of operations to achieve one indexing cycle of the invention. The selected interval of the timer relay TR will depend upon the extent of exposure desired for a particular production run of irradiated exposures; the TR interval is therefore indicated as a shaded strip running, from the close of the index cycle, to the commencement of the next index cycle. Timer TR will be understood to include normally open contacts TR-l at L-3, in series with manual on-off switching, for initiating the index cycle, by completing the circuit to solenoid 1B for upper and lower shield door actuators 40-41, to open the outer doors 36-37; once the doors move from closed position, the switches LS-14 and LS-IS are allowed to close, to enable the R1 relay circuit (at L-18). In terms of the illustrative cycle of FIG. 17, it takes 3 seconds to achieve door opening and doors 36-37 remain open until outer door closing operations commence (after the 9th-second), as determined by dropout of relay R2; relay R2 will be seen in FIG. 16 to have contacts which operate to reverse outer door actuators 40-41, by shifting excitation from solenoid IE to solenoid 1A.

During the interval in which the outer shield doors are open, the load-in or transfer actuator 28 is operated for one IN-OUT reciprocating cycle, to displace container 26 from the conveyor accumulator 25 to the in-wall position, designated 26'; the chart of FIG. 17 illustrates consecutive 3-second allowances for the IN" and OUT" strokes of this cycle, being determined first by solenoid 2B and then by solenoid 2A for the actuator 28. the IN stroke begins when LS-l0 and LS-II are closed to signify full opening of the outer doors 37-37; this is shown at L-6 and L-7 where the circuit to solenoid 2B is completed. At the same time (at L-6), the circuit is completed to motor relay MR-l for the exit conveyor motor, to operate the exit roller system 29 for discharge of a fully processed container, from the in-wall lock" position, to the exit ramp 30 (FIG. I); relay MR-l is operative to drive the roller system 29 until LS-IO and LS-ll open the line L-6, upon commencement of closure of the outer doors 36-37.

When the load-in actuator 28 is full in, LS-l2 closes at L-l9 to pick up relay R1, which is held in by its stick contact Rl-l (at L-l8) until outer doors 36-37 are closed. Relay R1 is immediately operative at L-7 and L-8 (contacts R1-3 and R14) to reverse the solenoid control for actuator 28, returning the same to its fully retracted position, monitored by LS-l3; closure of LS-13 (at L-S) then picks up relay R2 which holds in through its stick contact R2-3 (L-4) until dropout by contact Rl-2 when relay R1 is deenergized.

At the time when relay R2 picks up, relay R3 is also picked up by contact R2-4 (at L-20). Relay R3 is the basic determinant of the described matrix operation; it is held in by its stick contact R3-1 (at L-21) until contact R7-1 (at L-2l) of relay R7 opens, to signal completion of all index cycle operations and initiation of the preselected time interval of the timer relay TR (L-26, L-27). Once relay R3 drops out, its contact R3-4 (at L-26) opens to drop out relay R7.

Having closed the outer doors 36-37 (after the 12th second), with the basic'relay R3 held in, and with a loaded new container in the in-wall .locked position 26' (FIG. I), the internal matrix loading, shifting, and unloading functions may proceed. This involves raising the elevator systems 53-54-55 to their up positions depicted in FIG. and actuating the inner shield doors 35-38 from closed to open positions; both these actuations are initiated when LS-I4 and LS-IS become closed, to certify that the outer shield doors 36-37 are fully closed. At L-l4, the up elevator solenoid 3B is excited to raise all elevators, and at L-l6 the solenoid 4B is excited to actuate the inner doors 35-38 to OPEN" position. In the present illustrative case, three seconds are allowed for inner door opening and for elevator raising, and the achievement of all these functions is signalled by limit switches, LS-16, LS-l7, LS-18, LS-20, and LS-2I monitoring the respective different displacements.

Achievement of the FIG. 5 relation is certified by concurrent closure of the indicated limit switches at L-l0,thus completing the circuit to solenoid 5B and initiating outward displacement of the push bar systems 56-62. Upon achievement of the push bar OUT positions (18th second; FIG. 6 relationship), switches LS-32 and LS-33 are closed (at L-ll) to complete the circuit for the motor relay MR-2 which will be understood to be part of the drive system for the load-in conveyor rolls, both those within the wall inlet passage 16 and those on the load-in platform 75 (FIG. A). These conveyor rolls feed the new container from the in-wall position 26 to stops I50 on platform, at which point LS-22 is closed (at L-22) to pickup relay R4. Relay R4 is held in by its stick contact R4-l (at L-23), until the normally closed contact R6-l of relay R6 is opened, about I second later. The l-second interval is provided to assure accomplishment of the several functions controlled by relay R4; the delay is initiated by closure of contacts R4-5 (at [1-28) to a time delay relay TD, which, after I second, closes its contact TD-l (at L-25) to pickup relay R6.

Aside from the safety delay just described, relay R4 is operative at L-l2 and L-l4 to reverse the elevator controls by exciting the DOWN solenoid 3A and deenergizing the UP solenoid 38, thus advancing the matrix to the FIG. 7 position, by the 24th second. Relay R4 also disconnects the load-in motor relay MR-2, by breaking the nonnally closed contact R4-4 (at L-ll).

Upon elapse of the I-second delay, relay R6 will be picked up (at L-25), providing that various interlocking switch functions have been accomplished; namely: LS-23, LS-24, and LS-25 closed, to certify that all elevators are in DOWN" position. Relay R6 remains picked up until the normally closed contact of LS-3l (at L-25) opens, upon full closure of the inner upper shield door 35. Aside from dropping out relay R4 (at L-23), relay R6 activates motor relay MR-3 (at L-l7) which will be understood to be operative upon both the motor drive to the matrix exit roller conveyor 29; this drive is effective to remove the fully processed container C-l from the matrix and into the wall passage 17, to the point where the container strikes switch LS-27, to open its normally closed contacts (at L-l7). This event signals that the processed container is sufficiently positioned within the cell wall, so that the inner doors 35-38 may be closed.

At line L-24, it will be seen that closure of the normally open contacts of switch LS-27 is operative to pickup relay R5, which is immediately effective at lines L-9 and L-l0 to reverse the excitation of the push bar actuating solenoids 5A-5B, thereby advancing the matrix to the FIG. 8 relationship. Relay R5 is also immediately effective (at L-IS and L-16) to reverse the excitation of the solenoids 4A-4B, thus actuating the inner upper and lower shield doors 35-38 to CLOSED position. Achievement of these functions is signaled by switches LS-28 and LS-29 (for the push bar IN" position) and by switches LS-30 and LS-3l (for the CLOSED" condition of inner doors 35-38), thus certifying that the indexing cycle is functionally complete and that the selected timer interval may be operative. These functions are established at L-26 and L-27 (to start the timer relay.) and to pickup relay R-7; as previously explained, the contact R7-l (at L-2l) is then briefly opened to disconnect relay R3, which thereupon drops out relays R-5 and R-7 at lines L-24 and L-26.

The automated index cycle is now terminated, with all relays dropped out (except for the timer relay TR), with all shield doors closed, and with the matrix in the FIG. 8 condition. The cycle, of course, repeats upon completion of the selected timing, at which point the timer contacts TR-l close again, at Ir3.

CONCLUSION It will be appreciated that the described mechanism meets the stated objects, wit basically simple structure that affords a high degree of efficiency for the irradiated exposure of production runs of filled containers. The mechanism of course contemplates rather substantial investment, based on an estimated processing capacity. But it is a further feature of the invention that, once the initial production capacity appears to become saturated, there can be a subsequent doubling or other substantially multiplied capacity, without anything like the original investment outlay. This inexpensive substantial expansion of capacity is attributable to the modular nature of the construction of the invention, both as to framework and as to indexing displacements. FIGS. 18 and 19 illustrate a first modification reflecting these important features, and FIGS. 20 to 25 illustrate a further modification.

In FIG. 18, the basic cell structure will be recognized and therefore certain parts will be given the same reference numerals as for the preceding basic device. It suffices to note that merely by the simple expedient of providing an overall length X, to define an elongated interior length dimension X, there can be a multiplication of production capacity, served by additional radiation sources, such as the source 10'. In the form of FIG. 18, production capability is substantially doubled by concurrent use of two like sources 10-10, served by like cask systems 13-13 which are capable of positioning their respective sources at a center-to-center spacing D from each other; the spacing D represents the effective width of the central elevator unit 54 already described in connection with FIGS. 5 to 10, and this spacing D is essentially the limit of extended interior length X required over the corresponding minimum clearance involved in the simpler system. It is of course a simple matter to make cell 11 to such dimensions in the first place, i.e., even if only the system of FIG. 1 is to be installed. It will be seen that in FIG. 18, the only modification to cell structure then necessary is to provide the opening in wall 18 to accommodate the additional cask and source l3'-10'.

In FIG. 19, the additional source 10 is seen to serve two vertically aligned banks of containers in precisely the same manner as described in connection with source 10 (FIGS. to 8), there being again four tiers of the matrix above, and four below, the common effective horizontal plane of the sources 10I0'. The 40 containers shown within the multiple system of FIG. 19 follow the sequentially indexed course denoted by arrows, the container 041 having just been loaded in (at platform level 75, of the right-hand elevator system 55); at this point in time, containers C-31, C-2l, C11, and C-1 are also on the elevator system 55, with C-I in the exit position, ready for discharge by the roll conveyors (29-29). The left-hand elevator system is shown accommodating containers C-36, C-26, C-I6, and C-6. The remaining containers are all carried by an expanded-width central elevator 54', which exceeds by the distance D the effective width of the previously described central elevator 54. This extended width provides for two vertical banks of containers which at any single indexed condition are served primarily by the source 10', and two further vertical banks served (at the same time) primarily by the other source 10. Since in the course of their indexed progression all containers get exposures directly to both sources 10-10, the total exposure accumulation for any single container is achieved in substantially one-half the previous time, so that twice the previous number of containers may be accommodated in a given time.

It will be appreciated that the system of FIG. 19 is illustrative, not only of the double-capacity system shown, but also as to any desired multiple of a basic elemental capacity system. Thus, by providing three sources, i.e., one in addition to sources 10-10, with each source serving primarily its own two vertical banks of containers, and by fabricating the central elevator system to simultaneously raise all pairs of vertical banks served by the respective sources, there may for example be provided an effective trebling of capacity, as will be understood.

FIGS. 20 to 28 illustrate a modified mechanism by which capacity and efficiency of the basic transport system of the invention can be even further enhanced, and in which there may be a vast increase in efficiency of radiation source utilization, particularly for the case of relatively low-density loading of containers, as when sterilizing medical products and devices. Generally, this modification utilizes containers which may be of the nature and proportions already described, but the transport mechanism is of doubled depth so that two end-to-end oriented containers can be processed through the cell at each indexed location within the mechanism. Thus, the containers, of length L,, in doubled end-to-end relation, have a combined length 2L,, as indicated in FIG. 21; and it is convenient to refer (a) to containers previously identified as being in a front cluster, and (b) to additional containers as being in a rear cluster, all as indicated by legend in FIG. 21. It is also convenient to handle such pairs of containers as a unit, as suggested by the use of an elongated supporting box or tray 159 having outwardly projecting end support lugs 45 analogous to those described at 45 in FIG. 4; the basic container transport mechanism will thus be understood to transfer and position each pair of end-to-end related containers, as a unit, by way of the lugs 45 on the box 159.

In FIG. 20 and 21, it is seen that the transport path and its relation to the irradiation source may be of the nature already described for either of the forms of FIG. I or FIG. 19, but there has been selected in FIGS. 20 and 21 a system corresponding to that of FIG. 19. In fact, FIG. 19 serves not only to illustrate the path of indexed container progression through the modification of FIGS. 20 and 21, but also to illustrate container relation to multiple sources 10-10. For this reason, reference numeral identification in FIGS. 20 and 21 follows that used in FIG. 19, the containers in the front cluster being identified C-l to 0-41, inclusive, as in FIG, 19, and the corresponding containers in the rear cluster being similarly identified, but with primed notation. It will be understood that, for each indexed cycle in FIGS. 20 and 21, end-to-end pairs of containers receive the same displacement through the transport matrix; thus, for example, the newly introduced paired containers C-41 and C-41 are simultaneously lowered from platform level 75 to the first tier of the matrix, into adjacency with the paired containers C40 and C-40, and other pairs receive displacements already described.

The system of FIGS. 20 to 28 utilizes a source or sources which may be slightly shorter than the length L, described in FIG. 4. In fact, the source (10') length is shown in FIG. 21 to be substantially the effective length L of each container, the orientation being such that adjacent half-lengths of paired containers (e.g., C-17' and C-17) always receive maximum dosage, regardless of their indexed position within the matrix, for any complete transport course through one cluster of the matrix. According to a feature of the invention, the end-forend relationship of the containers in the clusters is then reversed, so. that what had been outer half-lengths of all containers in their first transport course can become inner halflengths of all containers in their second transport course.

The end-for-end container reversal feature can be achieved by various mechanisms. For example, means can be provided within the cell to accomplish container reversal as each container or pair of containers completes its first course through the matrix. If totally unexposed containers are introduced as end-to-end adjacent pairs, then both the individual containers of each such pair must be end-for-end reversed after completing a first transport course and prior to starting the second transport course through the matrix. In another mode of operation, in which only one unexposed container is introduced to the cell at each index cycle, the unexposed container is loaded into the transport start location for one cluster (e.g., the front cluster) contemporaneously with displacement of the most exposed container of the front cluster to the start position of the second cluster; a container would only be fully exposed after progression through both front and back clusters, and only one exposed container would be delivered through the exit passage of the cell, for any given index cycle. However, we indicate our preference for the form shown in FIGS. 20 and 21, wherein the end-for-end reversal of containers is accomplished outside the cell, as an inherent function of modified mechanism for handling containers delivered to and removed from the cell, at the ports 16-17 already described.

Basically, the embodiment of FIG. 21 achieves end-for-end reversal of container exposure to the irradiation in the cell, by always loading in an unexposed container, paired end to end with a container which has also run the course of one of the clusters (e.g., the front cluster), and by simultaneously extracting from the cell a pair of containers in which one (container of the pair) has run the course of the front cluster and in which the second (container of the pair) has run the course of the rear cluster. The mechanism outside the cell selects an unexposed container, such as container 26, from the load-in conveyor 25' (which may be as described at 25 in FIG. I), and pairs it with a justextracted container 26a which has completed its course through the front cluster within the cell; in the same index cycle, this mechanism also (a) delivers a fully exposed container 26b to a load exit conveyor 30', which may be similar to conveyor 25', except for its direction of motion (indicated by an arrow), and (b) so longitudinally displaces the container 26a into position for pairing with the container 26 that container 26a may be progressed through the rear cluster as container 26 is progressed through the front cluster. FIG. 20 shows the instant of time when the paired containers 26-26a (nested in a larger box or tray 159) have been positioned by first or primary elevator means 160 at an upper elevation, identified level C, at which the paired containers 26-16a are aligned for displacement by horizontal actuator means 162 (which may be analogous to that described at 28 in FIG. 1) into the load-in port 16 of the cell; as will later be more clear, a pair of retractable, opposed, position-holding guides or rails 166 is operative to retain this raised position (see also FIG. 22A), with containers 26-26a, nested in box 159, in readiness for their load transfer actuation by means 162, into port 16. Meanwhile, opportunity is afforded to return elevator to level A, in readiness to accept discharge of exposed containers from the cell wall at 17.

The inner and outer doors for establishing radiation lock functions at ports 16 and 17 have already been described and therefore need not be repeated for the embodiment of FIGS. 20 to 28; they will, of course, be understood to be provided, with suitably synchronized actuation in relation to the cell loading and discharging functions already described.

The elevator means 160 may be one of a variety of available constructions. It is, therefore, shown schematically by heavy vertical phantom lines, suggesting the spaced lift guide paths thereof, with similarly spaced vertically positionable means (such as horizontal bars 160') for lifting engagement with the container box lugs 45, as more clearly appears in the sequence diagrams of FIGS. 22 to 27. The lift bars 160' are seen (e.g., in FIG. 23) to nest into suitably recessed parts of the frame or floor, when elevator 160 is in the down position (level A), so that a clear path is available for reception of exposed containers discharged from port 17.

The elevator means 160, and a secondary elevator means 163, will be understood to include level-positioning control mechanism which relies upon fixed level position sensors, as suggested by heavy arrows identified with different levels A, B, and C. The primary elevator is operative to position a box tray 159 between the lower level A and the most elevated level C, corresponding to the levels of the cell ports 17-16, respectively. The secondary elevator 163 includes a horizontal platform which provides substantial bottom support for both containers of a given pair, such support being independent of the edge support afforded by bottom flanges of the box tray 159 (see FIG. 22A); elevator 163 is operative between level A and the intermediate level of the load-in and exit conveyors 25 a% The cycle of container shifting, or exposed-end reversal, will be described in connection with the succession of fragmentary diagrams of FIGS. 22 to 27 together with the timer program layout of FIG. 28. The layout of FIG. 28 has been simplified to show merely the relative timing of the more significant functions, in relation to the index cycle already described for the program of FIG. 17, and it will be understood that solenoids, relays, retractable stops and clamps, limit switches and the like may be provided, as needed, by those skilled in the art to accomplish the indicated programming of an operative cycle. For clarity of distinguishing the half-exposed containers in FIGS. 22 to 27, double cross hatched shading has been adopted.

FIG. 22 schematically depicts the start (or zero) time for the illustrative indexing cycle (FIGS. 28 and 17). The mechanism has held this relationship during the dwell, for irradiation exposure between successive indexes. And the holding rails 166 have kept the half-exposed container (26a), paired with the unexposed container (26), in readiness for transfer into port 16. According to the program (FIG. 28), such transfer occurs after the third second, when the outer doors (not shown in FIGS. 20 to 27, but see FIG. 17) have opened; by the end of the sixth second, actuator 162 has transferred these containers and their box tray 159 into the wall lock 16, in good time to permit actuator 162 to retract before the outer doors close. Actuator 162 thus completely replaces the function of the analogous actuator 28 in FIG. 1.

Meanwhile, between the third and seventh second, and while the outer doors are still open, the wall-exit roller (29) drive has been operative to expel the container pair comprising half-exposed container 26a and fully exposed container 26b, together with their supporting box tray 159, into seated relation on the elevator platform 163, it being understood that retractable positioning or stop means (not shown) may assure accurately discharged positioning of these containers. Such positioning is complete by the end of the seventh second, when the mechanism and the containers appear as in FIG. 23.

The next function occurs in the ninth to l lth seconds, when the secondary elevator 163 lifts the exposed containers 26a and 26b, out of nested retention by box 159 and up to level B (FIG. 24). Upon attaining this position, actuator 164 is operative to discharge, onto the exit conveyor 30, the fully exposed container 26b, thus leaving the platform of elevator 163 laden only with the half-exposed container 260. Upon retraction of actuator 16 (l lth second), the secondary elevator descends to return the half-exposed container 26a to level A (FIG. 25), where actuator 165 is caused to shuttle the half-exposed container 26a to the position (phantom outline in FIG. 25) just previously occupied by the discharged fully exposed container 2612.

By the end of the 17th second, container 26a has been shuttled and actuator 165 has retracted, to clear the way for another lift cycle of the secondary elevator 163, again to level B (FIG. 26). On this occasion, the shuttled displacement of container 26a has cleared the way for loading the next available unexposed container 26, from load-in conveyor 25' and onto the platform of elevator 163, as by operation of suitable escapement transfer mechanism forming part of conveyor 25' and operative in the interval indicated in FIG. 28 19th to 21st seconds).

End-for-end reversal has now been accomplished on the secondary elevator 163, and the containers 26-26a are ready to be nested in the box tray 159 served by the primary elevator 160. The transfer from the secondary to the primary elevator may take place through sequenced or concurrent operations of the two elevators, and the latter alternative is illustrated, in order to conserve cycle time. Thus, in FIG. 27, the rise of elevator 160 (with box tray 159) has picked up containers 26-26a while elevator 163 is being returned to level A.

It should be noted that during the operation of FIGS. 23 to 27, the holding or positioning guide rails I66 remain retracted, as, for example, laterally away from the respective sides of the vertical swath or path of movement of the loaded elevator 160. Thus, the way is clear for elevator 160 to reach level C, whereupon the guide rails 166 are actuated into boxholding position (FIG. 22A), thus allowing elevator lifts 160' to return to level A. The system thus requires the appearance of FIG. 22, and all is in readiness to repeat the described cycle after lapse of the predetermined dwell, for irradiation purposes.

It will be appreciated that by having dropped the partially loaded secondary elevator (from level B to level A, FIGS. 24 and 25), it is possible to utilize the box tray 159 as a precise guide while means is operative to shuttle the half-exposed container 26a to its new position. Of course, with suitable guides, etc., to assure precise shuttling displacement, there is no reason why shuttling could not have taken place at level B, thus permitting a quick sequence of operation of actuators 164-165 and the escapement transfer function of conveyor 25, all prior to returning elevator 163 to its lower position. In any event, it will be understood that frame-referenced clamp means (not shown) may be employed to secure box tray 159 during the shuttle operation (FIG. 25), and that analogous frame-referenced means is provided if shuttling is desired at level A.

The described expanded system of FIGS. 20 to 27 will be seen to provide substantially enhanced use of the irradiation capability of a given source or sources, without impairing the index cycle time or the rate at which containers are fed into and extracted from the cell. The box tray 159 is, like the basic containers themselves, of aluminum or other suitable material transparent to the radiation. The product is caused to overlap the source in all planes, and this result is achieved with a source that is substantially only the length of a single container. The improved efficiency is achieved without adding to the complexity of mechanism within the cell, and basic simplicity characterizes the additional operations external to the cell.

While the invention has been described in detail for the preferred forms shown, it will be understood that modifications may be made without departing from the scope of the invention as defined in the claims.

What is claimed is: 

1. A transport system for the sequential unit progression of plural like containers in a two-coordinate matrix of plural spaced tiers of plural containers, the path of movement of containers through said matrix comprising entry and sweep along one coordinate at a constant value of the other coordinate, followed by transfer to another value of said other coordinate for reverse sweep along said other coordinate and then transfer to a third value of a said other coordinate, and thereafter recycling the sweeps of said one coordinate at successive different values of said other coordinate; said system comprising a frame; first-coordinate transport means including framereferenced guide means confining displacement along a first coordinate and first actuating means having an effective stroke of at least the spacing between two of said tiers, said firstcoordinate transport means including container support means having releasable engagement with an end container of one of said tiers; second-coordinate transport means including a first transport element with frame-referenced guide means confining displacement along the second coordinate, said first transport element including container support means having releasable engagement with containers of one of said two tiers, a second transport element with frame-referenced guide means confining displacement along the second coordinate and offset from said first transport element, said second transport element having releasable engagement with containers of the other of said two tiers; second actuating means for cycled reciprocation of said first and second elements in opposite directions of the second coordinate; and means establishing a synchronized interlacing of the reciprocating cycles of said first and second actuating means.
 2. A transport system according to claim 1, in which said first and second transport elements each includes plural members at at least double-tier spacing, the members of said first transport element being offset from and in interlaced overlap with the members of said second transport element to the extent of substantially a one-tier offset.
 3. A two-coordinate transport mechanism, for the sequential unit progression of plural like containers in an upstanding two-dimensional matrix of plural vertically spaced tiers of plural containers, the path of movement of containers through said matrix comprising entry and sweep along a horizontal pass at a first elevation, followed by transfer to a second elevation and reverse sweep along a horizontal pass at said second elevation and then transfer to a third elevation, and thereafter recycling the horizontal sweeps at successive different elevations; said mechanism comprising a frame; upstanding elevator means including frame-referenced guide means and vertically reciprocable actuating means having a stroke of at least the spacing between two of said tiers, said elevator means including container support means beneath a supportable part of an end container of one of said tiers; first and second push bar means horizontally reciprocably guided by said frame means, said first push bar means including a horizontally elongated member aligned to pass beneath supportable parts of containers of one of said two tiers, said second push bar means including a horizontally elongated member aligned to pass beneath supportable parts of containers of the other of said two tiers; reciprocation-actuating means for cycled reciprocation of said first and second push bar means in opposite horizontAl directions; and means establishing a synchronized interlacing of the vertical reciprocating cycle of said first actuating means with the horizontal reciprocating cycle of said horizontal actuating means.
 4. Transport mechanism according to claim 3, in which said first push bar means is supported from one horizontal end of said matrix and passes beneath supportable parts of all containers of said one tier, being reciprocably displaceable between a first position in and a second position out of supportable engagement with the container of said one tier most remote from said one end; and in which said second push bar means is supported from the other end of said matrix and passes beneath supportable parts of all containers of said other tier, being reciprocably displaceable between a first position in and a second position out of supportable engagement with the container of said other tier most remote from said other end.
 5. Transport mechanism according to claim 4, in which said first push bar means includes two like vertically spaced horizontally elongated members respectively aligned to pass beneath supportable parts of containers of each of a first set of spaced tiers; and in which said second push bar means includes two like vertically spaced horizontally elongated members respectively aligned to pass beneath supportable parts of containers of each of a second set of spaced tiers that is interlaced with the tiers of said first set; said elevator means including at one end of said matrix spaced first and second container support means respectively beneath supportable parts of end containers of said first set of tiers, said elevator means also including at the other end of said matrix spaced first and second container support means respectively beneath supportable parts of end containers of said second set of tiers.
 6. Means for the production line substantially uniform irradiation of a material to be irradiated, comprising an elongated source of radiation and means for supporting the same with its elongation axis generally horizontal, a plurality of like elongated rectangularly prismatic containers essentially transparent to the radiation for containing unit quantities of the material to be irradiated, two-coordinate transport mechanism supporting plural tiers of plural containers in relatively closely nested relation in a first matrix vertically offset above said source and supporting plural tiers of plural containers in relatively closely nested relation in a second matrix vertically offset below said source, the path of movement of container movement through said matrices comprising successively reversed generally horizontal passes at each of a succession of vertical elevations first through one of said matrices and then through the other of said matrices; said transport mechanism comprising first horizontal push bar means at a first plurality of tier levels in both matrices, second horizontal push bar means at a second plurality of tier levels in both matrices, and vertical elevator systems at opposite ends of said matrices and serving plural tier levels in both said matrices; horizontally acting means for actuating said first and second push-bar means in opposed-phase reciprocation, vertically acting means for actuating said elevator systems in a cycle of vertical reciprocation; and means synchronizing the timed interlace of said horizontally acting means with said vertically acting means.
 7. Means according to claim 6, in which a cycle of operation comprises timing means determining a dwell between each succession of said timed interlace, whereby said containers move progressively through first one and then the other of said matrices in a succession of periodically indexed displacements between dwells.
 8. Production line means according to claim 7, in which synchronizing means determines a single coordinated cycle of said transport mechanism, whereby for each such coordinated cycle there is a one-container advance for all containers in both maTrices, said timing means being operated by completion of said synchronizing cycle and connected to reinitiate the cycle of said synchronizing means upon lapse of a predetermined time interval between synchronizing cycles, whereby container exposure to said source is determined by said synchronizing cycle and time interval.
 9. Production line means according to claim 8, in which said timing means is selectively adjustable, whereby a range of source-exposure times is available by adjustment of said timing means and without need to change said synchronizing cycle.
 10. Means according to claim 7, in which said containers are accommodated in end-to-end horizontally aligned pairs as they progress through said matrices, said source being of substantially one half the effective length of each container pair and being supported symmetrically between the spaced vertical planes of movement of the ends of said pairs, and container pair orientation-reversing means operative as each container pair completes its course through both matrices, said last-defined means having a cycle of operation that is synchronized with said periodic indexing displacements and that is effected in the period between dwells.
 11. Means according to claim 7, in which shield means surrounds said source and transport mechanism and has inlet and outlet radiation ports respectively communicating with inlet and outlet locations in said transport mechanism, separate shield gates for selectively opening and closing said ports, and gate-actuating means having a gate opening and closing cycle synchronized with the indexing period between dwells.
 12. Means according to claim 11, in which said shield gates are provided at outer and inner ends of each of said ports, thereby defining a radiation lock at each port, said locks being of length accommodating at least one container length, and means interlacing the open-and-close cycles of the two gates for each port, whereby each port is always shielded.
 13. Means according to claim 12, in which load transport means aligned for external communication with the inlet port includes periodically operative load-in control means, and in which load-discharge means aligned for external communication with the inlet port includes periodically operative load-out control means, and means interlacing the cycles of said respective control means during the respective open phases of operation of said outer gates.
 14. A transport system for the sequential unit progression of plural like elongated rectangular prismatic containers in a two-dimensional matrix of plural vertically spaced adjacent tiers of plural horizontally adjacent containers, the two dimensions of said matrix establishing a vertical plane and the container elongation axes being horizontal and normal to said plane, each longitudinal end of each said container including an axially outwardly projecting lifting lug, the path of movement of containers through said matrix comprising entry and sweep along a horizontal pass at a first elevation, followed by transfer to a second elevation and reverse sweep along a horizontal pass at said second elevation and then transfer to a third elevation, and thereafter recycling the horizontal sweeps at successive different elevations, said system comprising a frame, first push bar means including two parallel bars spaced substantially the length of a container and guided for horizontal movement in said frame along the horizontal dimension of said matrix at the elevation of one of said tiers, the containers of said one tier being supported at their lugs on the bars of said first push bar means, said first push bar means including a first actuator for the unitary guided horizontal displacement of all containers of said one tier, second push bar means similar to said first push bar means and including two frame-guided bars at the elevation of another of said tiers and supporting at their lugs the containers of said other tier, said second push bar means including a seCond actuator for the unitary guided horizontal displacement of all containers of said other tier, elevator means guided for vertical movement in said frame and including actuating means for selectively lifting the containers in both tiers in a cycle of intermittent displacement involving a first direction out of supported relation with said bars and a second direction back into supported relation with said bars, and means synchronizing the operation of said first and second actuators in a common cycle of opposed-phase intermittent displacements, said last-defined means also synchronizing the respective intermittent displacements of said cycles in interlaced relation.
 15. The system of claim 14, in which said first push bar means serves plural odd-numbered tiers and said second push bar means serves plural even-numbered tiers, and in which said elevator means comprises a first elevator at one end of said matrix with container support means at double-tier spacings and having a cycle of vertical movement from odd-numbered tier levels to even-numbered tier levels and return, a second elevator at the other end of said matrix with container support means at double-tier spacings and having a cycle of vertical movement from even-numbered tier levels to odd-numbered tier levels and return, the up and down strokes of said first and second elevators being synchronized.
 16. The system of claim 15, in which said elevator means includes a third elevator intermediate said first and second elevators with container support means at adjacent tier levels and having a cycle of vertical movement which is less than the tier-to-tier spacing but which is sufficient in its ''''up'''' position to support all containers vertically aligned therewith and in its ''''down'''' position to have released all containers vertically aligned therewith into support relation with said push bar means.
 17. The system of claim 15, in which the container support means of one of said elevators includes at one container support level a roll conveyor defining essentially a surface of container support, and drive means for said roll conveyor.
 18. The system of claim 17, in which the direction of container movement determined by driving the rolls of said conveyor is essentially horizontal and normal to said vertical plane.
 19. The system of claim 15, in which said frame includes, at one of the tier levels served by one of said elevators, a roll conveyor defining essentially a surface of container support, and drive means for said roll conveyor.
 20. Means for the substantially uniform production line irradiation of a material to be irradiated, comprising source means including an elongated source of radiation and means for supporting the same with its elongation axis generally horizontal, a plurality of like elongated rectangular prismatic containers essentially transparent to the radiation for containing unit quantities of the material to be irradiated, and an orthogonal two-coordinate transport mechanism supporting plural tiers of plural containers in a relatively closely nested matrix of vertically spaced adjacent tiers of plural horizontally spaced containers in proximity to said source; the two dimensions of said matrix establishing a vertical plane that is generally normal to the elongation axis of said source; the path of movement of containers through said matrix comprising successively reversed generally horizontal passes at each of a succession of different vertical elevations; said transport mechanism comprising a frame, said push bar means including two parallel bars spaced substantially the length of a container and guided for horizontal movement in said frame along the horizontal dimension of said matrix at the elevation of one of said tiers, the containers of said one tier being supported at their lugs on the bars of said first push bar means, said first push bar means including a first actuator for the unitary guided horizontal displacement of all containers Of said one tier, second push bar means similar to said first push bar means and including two frame-guided bars at the elevation of another of said tiers and supporting at their lugs the containers of said other tier, said second push bar means including a second actuator for the unitary guided horizontal displacement of all containers of said other tier, the push bars for one tier and said other tier having the same effective stroke length and being respectively at horizontal elevations above and below said source, elevator means guided for vertical movement in said frame and including actuating means for selectively lifting the containers in both tiers in a cycle of intermittent displacement involving a first direction out of supported relation with said bars and a second direction back into supported relation with said bars, and means synchronizing the operation of said first and second actuators in a common cycle of opposed-phase intermittent displacements, said last-defined means also synchronizing the respective intermittent displacements of said cycles in interlaced relation; said elevator means comprising a first elevator at one end of said matrix with container support means at one of said tiers and having a cycle of vertical movement from said one tier to said other tier and return, a second elevator at the other end of said matrix with container support means at the other of said tiers and having a cycle of vertical movement from said other tier to the next tier level in the direction away from said one tier, and a third elevator intermediate said first and second elevators with container support means at said one and said other tier levels and having a cycle of vertical movement which is less than the tier-to-tier spacing but which is sufficient in its ''''up'''' position to support all containers vertically aligned therewith and in its ''''down'''' position to have released all containers vertically aligned therewith into support relation with said push bar means.
 21. The system of claim 20, in which the effective width of said third elevator is an integer multiple of the displacement stroke of said push bar means.
 22. The system of claim 20, in which the effective width of said source is substantially the effective width of a container and in which said source is so positioned intermediate the width limits of said third elevator as to symmetrically overlap two adjacent column alignments for containers vertically aligned with said third elevator.
 23. The system of claim 22, in which said source means comprises a further source similar to said first-mentioned source and positioned in the horizontal plane of said first-mentioned source in spaced parallel relation thereto, the effective spacing of said sources being an integer multiple of the displacement stroke of said push bar means.
 24. The system of claim 22, in which said source means comprises a further source similar to said first-mentioned source and so positioned in the horizontal plane of said first-mentioned source and within the width limits of said third elevator as to symmetrically overlap a further two adjacent column alignments for containers vertically aligned with said third elevator.
 25. The system of claim 22, in which said source means comprises plural sources similar to and including said first-mentioned source and positioned in the horizontal plane of said first-mentioned source in spaced parallel relation thereto, said sources being spaced substantially an integer multiple of the displacement stroke of said push bar means.
 26. Means for the production line substantially uniform irradiation of a material to be irradiated, comprising a cell containing a source of radiation, a transport mechanism for the cyclic progression of a succession of like prismatic containers within said cell and in a regular progression of aspects with respect to radiation from said source, a wall around said cell opaque to the radiation and having inlet and outlEt port locks respectively communicating with start and finish locations at different elevations in said transport mechanism, container-handling means operative within said locks when open, and container-handling means external to said cell for loading said inlet port lock and unloading said outlet port lock; said last-defined means including load-in conveyor means having a first generally horizontal alignment of feeding, load exit conveyor means having a second generally horizontal alignment offset from said load-in conveyor means, and load transfer mechanism including elevator means displaceable from one to the other of said levels and in communication with each of said conveyor means at a particular elevation.
 27. Irradiating means according to claim 26, in which said elevator means includes platform means of sufficient elongation to simultaneously support two of said containers in end-to-end adjacency, the path of elevator movement of one of said supported containers intersecting the horizontal alignment of said load-in conveyor means and the path of elevator movement of the other of said containers intersecting the horizontal alignment of said load exit conveyor means, first container transfer means operative to discharge said other container from said platform at said second-mentioned intersection, second container transfer means operative to shuttle said one container on said platform to the position vacated by transfer of said other container, and third container transfer means operative to transfer a container from said load-in conveyor means to the position vacated by transfer of said one container.
 28. Irradiating means according to claim 27, and including plural like container-handling nesting means each accommodating two containers in end-to-end relation, said elevator means comprising primary and secondary elevators having a common vertical axis of movement, said primary elevator being operative only on said nesting means and said secondary elevator being operative only on said platform means, said platform means being clear of said nesting means at the elevation of container transfer to and from said platform means.
 29. Irradiating means according to claim 28, in which said second container transfer means is operative at a level in which said one container is retained by said nesting means, whereby shuttle action cannot disturb the alignment of said one container within the vertically elevated path of movement of said nesting means.
 30. Irradiating means according to claim 26, in which said transport mechanism is intermittently operated in an indexing cycle between dwells of predetermined duration, said locks and said container-handling means being synchronized for operation during said indexing cycle.
 31. Irradiating means according to claim 28, in which said nesting means is an elongated upwardly open box having an inwardly flanged open bottom through which said platform means may be displaced independently of said nesting means.
 32. Irradiating means according to claim 27, in which said intersections occur at a level intermediate the levels of said port locks.
 33. Irradiating means according to claim 26, in which said transport mechanism includes means subjecting each container to a first and then to a second full cycle of progression with respect to said source, and means operative successively on said containers at the conclusion of one and prior to commencement of the second of said full cycles for end-for-end reversal of one of said containers, whereby every container achieves a more uniform exposure to said source.
 34. Irradiating means according to claim 33, in which said end-for-end reversing means is part of said load transfer mechanism. 